Looking Back on the U.S. Space Shuttle Program, By the Numbers

The U.S. space shuttle program, which comes to an end in June, leaves a complicated legacy. No other craft has carried as many crew and as much cargo as the fleet of space planes, but they fell short on promises to lower launch costs. Expensive upgrades, a lapsing mission rate and two fatal accidents mar the shuttle's record.

"People don't recognize what an incredible piece of equipment and engineering the space shuttle was," says Mae Jemison, an astronaut who flew on Endeavour in 1992. "The magic left after the Challenger disaster. We started thinking it's dangerous and stopped thinking we could do difficult things." Atlantis is scheduled to perform the final mission, resupplying the International Space Station (ISS). NASA will then buy seats on Russia's Soyuz spacecraft to get astronauts into orbit; U.S. private companies have been tapped to deliver cargo to the ISS.